Everything You Need to Know about Narcissists, Psychopaths, and Abuse - click on this link: http://www.narcissistic-abuse.com/faq1.html
The mentally ill form dyads or couples. Pathologies attract each other and resonate in alliances of pain, fused relationships.
Such partnerships are suffused with torment: the mentally ill spouses or intimate partners engage in mutually hurtful conduct. It is also heartbreaking to watch your loved one's inexorable decline.
Gradually, the parties settle on coping strategies that are either "approach" or "avoidance" oriented.
The "approach" strategies include active denial of the problem often via a shared psychosis which renders the mental illness something to espouse, encourage, or be proud of.
Another strategy involves enabling. The enabler collaborates with the mentally sick partner so as to accommodate his or her disability.
Sometimes one of the partners assumes the role and mantle of guru, teacher, coach, guide, or father or mother. He or she suppresses dissent and re-molds the mentally ill partner to conform to some ideal. This could involve harsh or even sadistic criticism and humiliation on a daily basis as well as intermittent reinforcement.
But more often the mentally ill members of the dyad end up avoiding each other and the pain that they cause one another. This hurt aversion leads to extreme estrangement and cruel disengagement. Being ignored and neglected results in decompensation and acting out. The mentally ill partner tries to provoke attention and punish his or her avoidant counterpart by engaging in promiscuous and reckless behaviors.
In extreme cases the wayward partner internalizes and accepts the harsh judgment of her significant other. This can lead to major depressive episodes, psychotic disorders, and suicide.
(From the book "Malignant Self-love: Narcissism Revisited" by Sam Vaknin - Click on this link to purchase the print book, or 16 e-books, or 3 DVDs with 16 hours of video lectures on narcissists, psychopaths, and abuse in relationships: http://www.narcissistic-abuse.com/thebook.html)